Telephone message retrieval system with improved processor and retrieval console

ABSTRACT

A message retrieval system is disclosed which includes a plurality of answering machines, each connected to respected telephone line. Each answering machine records telephone responses on a respective message memory unit and all message memory units are connected to a single message processor. The message processor is in turn connected to a number of retrieval consoles used by operators to transcribe messages from the message memory units. The message processor operates (1) to automatically switch the mode of a headset included in the retrieval console between a transcription mode and a dialog mode to allow an operator either to transcribe messages or to conduct live telephone conversations via the same headset; (2) to allow a console to place a commanded message memory unit on hold while live telephone conversations are being conducted; (3) to disconnect a commanded message memory unit from a console in the event the console fails to command the message memory unit within a predetemined time; (4) to take positive action in the event recorded messages on one of the message memory units age excessively prior to transcription; and (5) to prevent a single operator closure of a switch or footpedal on the retrieval console from causing more than a preselected amount of transcription or rewinding of the message memory unit.

MICROFICHE APPENDIX

Included are three microfiche with 138 total frames.

BACKGROUND OF THE INVENTION

The present invention relates generally to telephone message recordingand transcribing systems, and in particular to an improved messageretrieval system for use with a telephone answering system whichincludes a plurality of telephone answering machines and a plurality ofmessage memory units coupled to the answering machines.

Telephone answering systems are routinely used to enable operatingpersonnel to service a large number of callers. Such systems include aplurality of answering machines coupled to telephone lines. Theseanswering machines deliver prerecorded messages after seizing a line andrecord caller responses on a message memory unit such as an endless looptape recorder. Operators then transcribe the recorded messages on themessage memory units and take appropriate action. For example, anoperator may call back a caller who has left a telephone number and arequest.

U.S. Pat. No. 4,338,494 discloses a microprocessor-controlled telephonecall inventorying and sequencing system. This system records priorityinformation (such as the time of recording of a message) along with thestored messages in the message memory unit. The microprocessor uses thisstored priority information to select which of the message memory unitsis to be interconnected with a transcribing station requestingtranscription. The selection criteria are chosen to prevent storedmessages on any particular message memory unit from being delayedexcessively in transcription. The system disclosed in the aboveidentified patent operates automatically to disconnect a message memoryunit from a transcribing station if the message memory unit has not beentranscribed from in a predetermined period, such as 60 seconds. In thisway, the system prevents an inactive transcribing station frommonopolizing a message memory unit.

Our previous U.S. Pat. No. 4,150,255 discloses a conversationaltelephone call distributor which utilizes a manually controlleddistribution panel to interconnect operator stations with selectedmessage recorders.

In spite of the many advantages offered by the systems described above,a need presently exists for an improved message retrieval system whichprovides improved protection against operator abuse of the system or thecallers, improved flexibility by which an operator can both transcriberecorded messages and respond to live telephone calls, and which takespositive action to prevent stored messages from being delayedexcessively in transcription.

SUMMARY OF THE INVENTION

According to this invention, an improved message retrieval system isprovided which provides important advantages in terms of safeguardsagainst operator error, safeguards against excessive delays in messagetranscription, and improved operator convenience.

According to a first feature of this invention, a retrieval console isprovided in a message retrieval system of the type generally describedabove. This retrieval console can be switched between a messagetranscription mode in which stored messages can be transcribed, and adialog mode in which the operator of the console can conductconversations via a telephone line. A single speaker, such as a headsetor handset, is provided for the operator, and the system operatesautomatically to interconnect the retrieval console with one of themessage memory units to allow stored messages to be transcribed by theoperator and heard on the speaker means of the retrieval console whenthe console is in the message transcription mode. Similarly, when theretrieval console is in the dialog mode the speaker means isautomatically interconnected with a telephone line such that theoperator can conduct a conversation on the telephone line using the samespeaker means as that used in the transcription of stored messages. Byautomatically changing the mode of the speaker means to maintain it incorrespondence with the mode of the retrieval console, the need for anoperator to change headsets, switch signal inputs to a headset, wearmultiple headsets, or have an external speaker is completely eliminated.In this way, operator efficiency is increased.

According to a second feature of this invention, a dual mode retrievalconsole is provided which can be used either to transcribe storedmessages from one of the message memory units or to conductconversations on a telephone line. A message processor is interconnectedbetween the retrieval console and the message memory units. This messageprocessor operates to interconnect each of the retrieval consoles withrespective selected ones of the message memory units to permit each ofthe retrieval consoles when in the message transcription mode to commandplayback of stored messages from the interconnected message memory unitand to ensure that each of the message memory units is connected to nomore than one of the retrieval consoles at a time. In addition, thismessage processor operates in the event one of the retrieval consoles isswitched to the dialog mode while interconnected with one of the messagememory units to prevent the interconnected one of the message memoryunits from being interconnected with another of the retrieval consoleswhile the one of the retrieval consoles is in the dialog mode. With thisfeature of the invention an operator transcribing a stored message caneasily switch to the dialog mode when necessary to conduct a telephoneconversation without losing control of the interconnected message memoryunit. Then, when the telephone conversation is completed, the operatorcan return to the interrupted transcription.

In order to prevent undesired monopolization of a message memory unitwhile an operator is using a retrieval console in the dialog mode, themessage processor preferably operates to disconnect a message memoryunit from a retrieval console in the event the retrieval console failsto command activity of the respective message memory unit within apredetermined time interval. In the preferred embodiment describedbelow, the message processor activates a warning alarm on the retrievalconsole prior to disconnecting the retrieval console from the messagememory unit in order to allow the operator to take action to preservethe connection with the message memory unit.

According to another feature of this invention, a message retrievalsystem of the type generally described above is provided with means formonitoring a parameter indicative of the age of messages stored inmessage memory units and for automatically generating an alarm signal inthe event the parameter exceeds a threshold indicative of excessivedelays between the time of recording and the time of playback ofmessages stored in the message memory unit. In addition, means areprovided for modifying the system in response to the alarm signal toadapt the system to excessive delays between message recording andplayback. For example, in the preferred embodiment described below, themodifying means operates to prevent further messages from being recordedon a message memory unit until the excessively old messages have beentranscribed. In this way, excessive callback delays are avoided.

Yet another feature of this invention relates to the manner in whichoperator control of a message memory unit is limited in order to preventmisuse of the system. According to this feature of the invention, atleast one retrieval console is provided in a message retrieval systemand is coupled to the message memory units to permit an operator at theretrieval console to transcribe messages stored on the message memoryunits. This retrieval console comprises at least one forward switchoperative to generate a playback command to cause one of the messagememory units to play back a stored message in a forward direction. Meansare provided for preventing a single activation of the forward switchfrom causing a selected one of the message memory units from playingback a stored message for more than a first preselected time interval.In this way, an operator cannot through inadvertence or intention simplylet messages be played out without transcription through a singleactivation of the forward switch. Rather, the operator must takerepetitive actions to maintain message playback. In the preferredembodiment described below, the retrieval console further includes atleast one reverse switch operative to generate a rewind command to causethe respective message memory unit to rewind a stored message in areverse direction, and the invention further comprises means forpreventing a single activation of the reverse switch from causing aselected one of the message memory units from rewinding for more than asecond preselected time interval. This feature of the invention makes itsignificantly less likely that an operator will accidentally orinadvertently go back to much earlier messages that have already beentranscribed and thereby duplicate information already entered forprocessing.

The invention itself, together with further objects and attendantadvantages, will best be understood by reference to the followingdetailed description, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a message retrieval system whichincorporates the presently preferred embodiment of this invention.

FIG. 2 is a block diagram of the message processor of FIG. 1.

FIG. 3 is a block diagram of the Unit Interface Card of FIG. 2.

FIG. 4 is a block diagram of the Console Interface Card of FIG. 2.

FIG. 5 is a block diagram of the Front Panel Board of FIG. 2.

FIG. 6 is a block diagram of the Master Controller Card of FIG. 2.

FIG. 7 is a block diagram of the retrieval console of FIG. 1.

FIG. 8 is a plan view of the front panel of the retrieval console ofFIG. 7.

FIG. 9 is a schematic state diagram of the message processor of FIG. 2.

FIG. 10 is a flow chart of the Timer Interrupt subprogram included inthe program of the message processor of FIG. 2.

FIG. 11 is a flow chart of the Transmitter Empty Interrupt subprogramincluded in the message processor of FIG. 2.

FIG. 12 is a flow chart of the Receive Timeout Interrupt subprogramincluded in the message processor of FIG. 2.

FIG. 13 is a flow chart of the Polling Subroutine called by subprogramssuch as the Receive Timeout Interrupt.

FIGS. 14a-14e together form a flow chart of the Receiver Ready Interruptsubprogram included in the program of the message processor of FIG. 2.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Turning now to the drawings, FIG. 1-14e provide various diagrams andflowcharts of a message retrieval system 20 which incorporates apresently preferred embodiment of this invention. The followingdiscussion will treat first the hardware, then the software, and finallythe operation of this system.

A. SYSTEM HARDWARE

As shown in FIG. 1, the message retrieval system 20 includes a messageprocessor 30 which is connected to a maximum of eight message memoryunits 26 in this preferred embodiment. Each of the message memory units26 is connected to a respective base unit 24, and each of the base units24 is connected to a respective telephone line 22. The base units 24 aretelephone answering machines which answer calls on the telephone lines22, deliver prerecorded messages, and then record the telephoneresponses on the message memory units. The message memory units (MMU's)26 are in this preferred embodiment endless loop tape recording machineshaving separate record and transcribe magnetic heads. This invention isnot directed per se to the structure or operation of the base units 24or the MMU's 26. These components are well known to those skilled in theart and will not be described in greater detail here. For example, thedisclosure of U.S. Pat. No. 4,338,494 describes telephone answeringmachines and MMU's which are suitable for use as the components 24,26 ofthis embodiment. Alternatively, the MMU's 26 may be embodied as solidstate recording devices.

The message processor 30 is in turn connected to a maximum of sixteenretrieval consoles 100. Each of the retrieval consoles 100 is powered bya power supply 140, and each of the retrieval consoles 100 isaccompanied by a foot pedal 110 and a telephone instrument 130, and aheadset or a handset 135, which is connected to the console 100 via aheadset adaptor 120.

The general operation of the message retrieval system 20 is that thebase units 24 serve to record telephone messages on the individual MMU's26. Operators at the retrieval consoles 100 are connected by the messageprocessor 30 with operator-selected ones of the MMU's 26. Onceconnected, an operator can use the retrieval console 100 to rewind ortranscribe from the connected MMU 26 in order to audit or transcribestored messages from the MMU 26. The operator hears the audited messagesvia the headset or handset 135. Once a message has been transcribed, theoperator will then typically take appropriate action, such as callingback the caller who left the message on the MMU.

As shown in FIG. 2, the message processor 30 is a computer-based systemwhich in this preferred embodiment is made up of a number of separatecircuit cards interconnected by a bus 90. The message processor 30includes a CPU Card 80, such as that marketed by Prolog as Part No.7801, which includes a microprocessor with 1K of random access memoryand space for 8K of read only memory. The microprocessor of the CPU Card80 is interfaced with the MMU's 26 via one or more Unit Interface Cards40. Similarly, the CPU Card 80 is interfaced with the retrieval consoles100 by one or more Console Interface Cards 50. A Front Panel Board 60 isprovided to allow entry of certain parameters, and a Master ControllerCard 70 is provided to allow serial I/O transmission between the messageprocessor 30 and the retrieval consoles 100. FIGS. 3-6 provide detailedblock diagrams of the Unit Interface Card 40, the Console Interface Card50, the Front Panel Board 60 and the Master Controller Card 70.

FIG. 3 shows a block diagram of one of the Unit Interface Cards 40. Eachof the Unit Interface Cards 40 communicates with the remainder of themessage processor 30 via the bus 90. Each of the MMU's 26 serviced by aparticular Unit Interface Card 40 provides three input signals: POWERON, MESSAGE PRESENT, and OUT OF TAPE. The POWER ON input indicateswhether the respective MMU is powered. The MESSAGE PRESENT inputindicates whether the respective MMU 26 has recorded a message which isready to be transcribed. The OUT OF TAPE input indicates whether therespective MMU 26 has recorded messages on all available tape and istherefore unable to record additional messages.

In addition, the Unit Interface Card 40 provides three output signals toeach of the MMU's 26 controlled by the card 40: FORWARD, REVERSE, andDISABLE. The FORWARD command causes the associated MMU 26 to transcribestored messages in a forward direction. The REVERSE command causes therespective MMU 26 to move tape past the transcription head in a reversedirection, i.e., to back up the tape. The DISABLE command prevents theassociated MMU 26 from recording additional messages. The Unit InterfaceCard 40 provides appropriate buffers and latches so as to interfacethese three inputs and three outputs of each of the MMU's 26 with theremainder of the message processor 30.

FIG. 4 shows a block diagram of one of the Console Interface Cards 50.Each of the Console Interface Cards communicates with the remainder ofthe message processor 30 via the bus 90. In addition, each ConsoleInterface Card 50 receives audio signals from each of the message memoryunits 26 via a unit audio bus 32. Serial I/O communications between theConsole Interface Cards 50 and the remainder of the message processor 30are accomplished via serial out and serial in data paths 52,54,respectively. The Console Interface Card 50 includes an analogmultiplexer 55 which can be controlled by the CPU card 80 to directanalog signals from any one of the MMU's 26 to the associated retrievalconsole 100 via console audio conductors 56. Similarly, the ConsoleInterface Card interfaces the serial transmission of binary data via theconsole data conductors 58.

FIG. 5 shows a block diagram of the Front Panel Board 60. The FrontPanel Board 60 includes three sets of thumbwheel BCD switches 62,64,66.The switches 62 can be used to enter any number between zero and 99hours, 99 minutes as a Message Alert Timeout (MAT) threshold describedbelow. Similarly, the switches 64 can be used to manually enter anynumber between zero and 99 hours, 99 minutes as a Unit Disable Timeout(UDT) threshold as described below. The switches 66 can be used to enterany number between zero and 99 minutes as a Console Release Timeout(CRT) threshold. In addition, the Front Panel Board 60 includes threerocker switches 68a,68b,68c used to enter three binary control options(Release Warning Audible (RWA), Stop Motion Audible (SMA), and UnitDisable Override (UDO) as described below). The Front Panel Board 60also includes a run indicator 69 which visually indicates whether or notthe message processor 30 is powered and its program is running.

FIG. 6 shows a block diagram of the Master Controller Card 70. TheMaster Controller Card 70 includes a UART circuit which accomplishesserial data transfer via the serial data paths 52,54 in cooperation withthe Console Interface Card 50. The UART circuit is a conventional priorart serial I/O controller familiar to those skilled in the art. Inaddition, the Master Controller Card includes a conventionaljump-on-reset circuit, an interrupt controller circuit, and aprogrammable timer circuit to perform the functions described below.

FIG. 7 shows a block diagram of one of the retrieval consoles 100. Asshown in FIG. 7, each of the retrieval consoles 100 includes amicroprocessor 150 which controls the console. Serial data transmissionvia the console data conductors 58 is controlled via a UART 152, andaudio signals transmitted by the message processor 30 via the consoleaudio conductors 56 are processed by an audio interface circuit 154 anda digital volume control 156. The audio output of the digital volumecontrol 156 is applied via an amplifier to an audio conductor 124.

The headset adapter 120 includes a relay which is controlled tointerconnect the audio conductor 124 with the headset via line 126automatically when the retrieval console 100 is being used to transcribemessages from one of the MMU's 26. In addition, the headset adapter 120receives an audio signal from the telephone instrument 130 via line 122.The relay of the headset adapter 120 is controlled to automaticallybreak the connection between the conductor 126 and the conductor 124when the retrieval console 100 is used to conduct telephoneconversations via the line 122 and to connect the lines 122,126automatically.

The retrieval console 100 includes a switch panel 158 which generatesbinary signals that are applied as inputs via a keyboard interfacecircuit 159 to the microprocessor 150. Similarly, the foot pedal 100provides input signals via the conductors 160 which are passed viaappropriate optoisolators and buffers to the microprocessor 150. Aneight-segment volume display 162 is controlled by the microprocessor 150to indicate the volume level currently selected at the retrieval console100. A total of eight message indicators 164 and a total of eightserviced indicators 166, as well as an array of additional indicators168, are also controlled via I/O ports included on the RIOT 174. Anaudio alarm 170 is similarly driven by signals generated at an I/O portof the RIOT 174. It should be understood that the RIOT 174 is aconventional prior art device which includes random access memory, aplurality of parallel input/output ports, and a programmable timer. Suchdevices are well known to those skilled in the art and will nottherefore be described in greater detail here. A run indicator 172provides a visual indication of the status of the retrieval console 100.

FIG. 8 shows a plan view of the console panel 180 of the retrievalconsole 100. For each of the eight possible MMU's 26 this console panel180 includes a respective unit selection switch 158e, a respectivemessage indicator 164, and a respective serviced indicator 166. Inaddition, the console panel 180 includes manually actuated switches anddisplays which control and indicate the following functions: Hold(158a,168a), Reverse (158b,168b), Stop (158c,168c), Forward (158d,168d).A release warning indicator 168e is provided along with a release switch158f. The volume controls 158g,158h can be used to raise or lower thevolume of the audio signal on the headset or handset 135, and theeight-segment visual display 162 indicates the requested volume level.Indicators 168a-168e are included in indicators 168 of FIG. 7, andswitches 158a-158h are included in the switch panel 158 of FIG. 7.

In this preferred embodiment, the retrieval console 100 is housed in aninternally metalized plastic case; it includes a plastic graphics panel;and the input switches are static-shielded membrane switches. Thegraphics panel defines windows for the various indicators which in thispreferred embodiment are LED's.

B. SYSTEM SOFTWARE

As explained above, both the message processor 30 and each of theretrieval consoles 100 includes a respective programmed microprocessor.The following discussion will take up first the program for the messageprocessor 30 and then the program for the retrieval console 100.

1. Message Processor

FIG. 9 shows a general state diagram showing the overall flow of theprogram of the message processor 30. As shown in FIG. 9, this programbegins with an initialization subprogram. After initialization has beencompleted, the message processor 30 then polls a selected one of theconsoles 100. It does this by sending in serial fashion a six-bytemessage, each byte containing 8 bits. The first five bytes define thestate of the various indicators and the adapter 120 included in theretrieval console 100, and the sixth byte is a check sum.

After all six bytes have been sent to the selected console, the messageprocessor 30 then waits for a two-byte response. The first byteindicates any key entries on the retrieval console 100 and the secondbyte is a check sum. After the two-byte message has been received, themessage processor then analyzes the response to determine whether theresponse was properly received and whether the check sum confirms theaccuracy of the response. If either the complete message is not receivedin a predetermined time limit or the message is determined to be inerror, the message processor recognizes a poll failure and advances topoll the next console. If, on the other hand, the received message fromthe console is considered accurate, the message processor acts on theresponse, as for example by initiating commanded movement of theassociated MMU, and then advances to poll the next console.

In this way, each of the retrieval consoles 100 is polled in sequenceand the message processor coordinates interconnections between the MMU's26 and the retrieval consoles 100, as well as commands from theretrieval consoles 100 to the associated MMU's 26.

The program for the message processor 30 is divided into fivesubprograms. FIGS. 10-14e provide detailed flow charts for four of thesefive subprograms and the Polling Subroutine. Except for initialization,the entire message processor program is interrupt driven. The followingdiscussion will deal with each of the five subprograms that make up themessage processor software.

a. Power On Initialization

This subprogram is executed whenever power is applied to the messageprocessor 30, or whenever the crash recovery circuit generates a reseton the system bus. This subprogram is entered under the control of theMaster Controller Card 70 and is responsible for initialization of allhardware substantially as follows.

With respect to the CPU Card 80, interrupts are disabled, the interruptmode is initialized, RAM is tested and cleared, and the stack pointer isset. With respect to the Master Controller Card 70, the UART is reset,disabled, and initialized, its receive buffer is cleared, the interruptcontroller is initialized, and the programmable timer is set up withCounter 0 as a baud rate generator, Counter 1 as a receive charactertime limit, and Counter 2 as a system clock. With respect to the ConsoleInterface Cards 50 and the Unit Interface Cards 40, all output ports arecleared. With respect to the Front Panel Board 60, the settings of thevarious switches 62,64,66,68 are read and stored in RAM. The timerinterrupt of the Master Controller Card 70 is then enabled on theinterrupt controller and CPU interrupts are enabled. Polling is theninitiated starting with retrieval console No. 16. Finally, the CPU card80 is started in an infinite wait loop.

b. Timer Interrupt

The second subprogram of the message processor 30 is the Timer Interruptsubprogram which is executed whenever the Master Controller Card 70timer generates a 10 millisecond interrupt. The Timer Interruptsubprogram (as flow charted in FIG. 10) saves appropriate CPU registers,updates a one-second scaler, and then determines whether or not thescaler indicates an even second. If not, the routine restores CPUregisters and returns. If the one-second scaler does indicate an evensecond, the subprogram then increments all MMU motion timers not at themaximum count. A separate motion timer is maintained for each of theMMU's 26 and is used to indicate the time the MMU has been in a givenmotion state (such as forward or reverse). Then the front panel switcheson the Front Panel Board 60 are read and stored in RAM and all MMUmessage timers not at maximum count are incremented. The programmaintains a separate MMU message timer for each of the MMU's 26. Thesetimers basically store the elapsed time since the MESSAGE PRESENT inputof the associated MMU 26 first indicated that a message was stored onthe MMU 26, and are reset to zero each time the MESSAGE PRESENT inputindicates that all stored messages have been transcribed. Then for eachof the eight MMU's a subroutine is performed to determine whether theMMU should be disabled and to update timeout variables and indicators.

For each MMU, first the message present indicator is examined. If nomessage is present then the message indicator bits used to drive theindicator 164 are set to the off configuration, the appropriate messagetimer is set to zero, and any disabled condition is cleared. If, on theother hand, a message is present on the MMU of interest, the subroutinethen checks to see whether the Message Alert Timeout switches 62 havebeen set equal to zero indicating that no timeout function is desired.If so, the bits controlling the message indicator 164 of the appropriateMMU 26 are set to the on configuration. If the Message Alert Timeoutfunction is enabled, the subroutine then checks to see whether themessage timer for the MMU of interest is greater than or equal to theMessage Alert Timeout threshold set by the switches 62. If so, thesubroutine then checks to see whether the rocker switch 68c has beenused to disable the Unit Disable Option. If not, the subroutine checksto see whether the message timer is greater than or equal to the sum ofthe times entered by the two sets of switches 62,64. If so, theappropriate MMU 26 is disabled and the bits controlling the associatedmessage indicator 164 are set to the 2 Hertz flash configuration. Ifnot, these bits are set to the 1 Hertz flash configuration.

After the subroutine has been executed for all of the MMU's, the CPUregisters are restored, interrupts are reenabled, and subprogramreturns. The Timer Interrupt subprogram ensures that the messageindicators 164 are properly controlled, and ensures that the MMU's 26are disabled in the event that the corresponding MMU message timerexceeds the preset threshold.

c. Transmitter Empty Interrupt

The third subprogram included in the software of the message processor30 is the Transmitter Empty Interrupt flowcharted in FIG. 11. Thissubprogram is executed whenever the UART of the Master Controller Card70 generates a transmitter empty interrupt indicating that transmissionof an 8 bit byte has just been completed. The Transmitter EmptyInterrupt saves necessary CPU registers, and transmits a single 8-bitcharacter from the transmit buffer to the UART. When all characters inthe transmit buffer have been transmitted to the UART and therefore tothe console, the UART receiver is reenabled and the receive time limitcounter is initialized to timeout in about the time required to transmit3 bytes. Then appropriate CPU registers are restored and the interruptsystem is reenabled before returning.

d. Receive Timeout Interrupt

The fourth subprogram, entitled Receive Time-out Interrupt, isflowcharted in FIG. 12. It is executed whenever the Master ControllerCard timer receive time limit counter generates an interrupt indicatingthat no characters have been received by the UART of the MasterController Card 70 within the specified time interval. This subprogramsaves whatever CPU registers are needed and then counts the number ofconsecutive times a retrieval console 100 has failed to respond to apoll. When this count exceeds a first threshold, the tape motion of anyMMU connected to the nonresponding retrieval console 100 is stopped.When the count exceeds a second threshold, any connected MMU isdisconnected from the nonresponding retrieval console 100. The UART ofthe Master Controller Card 70 is then placed in the transmit mode inorder to initiate polling of the next retrieval console. Finally,appropriate CPU registers are restored and the interrupt system isreenabled before returning from the subprogram. FIG. 13 is a flow chartof the Polling Subroutine called by the Receiver Timeout Interrupt.

e. Receiver Ready Interrupt

The fifth subprogram included in the message processor software isentitled Receiver Ready Interrupt and is flow-charted in FIGS. 14a-14e.This subprogram is executed whenever the UART included in the MasterController Card 70 receives an 8-bit character from one of the retrievalconsoles 100. The Receiver Ready Interrupt subprogram waits until bothbytes of a message from one of the retrieval consoles 100 is receivedand then examines the received message for UART errors and checksumerrors. If for any reason the response from the retrieval console 100 isnot satisfactory, the subprogram takes steps to ensure that anyconnected MMU is protected from a nonresponding console. In the event novalid response has been received from a console in the last 20 seconds,the console is disconnected from any previously connected MMU. In theevent no valid response has been received from a console in the last 1second, the subprogram operates to stop all tape motion on any MMUconnected to that console. Then the poll of the next console isinitiated, CPU registers are restored, the interrupt system isreenabled, and the program returns.

In the event a good response is received from the retrieval consolebeing polled and that console is presently connected to any of the MMU's26, the subroutine of FIG. 14b is executed. This subroutine checks tosee whether one of the unit keys 158e is depressed. If not, thesubroutine returns after restoring registers and reenabling theinterrupt system. If so, the subroutine takes three actions depending onthe status of the MMU designated by the depressed one of the unit keys158e. If the depressed one of the unit keys 158e corresponds to any MMUcurrently connected to the console, then the headset adapter 120 iscontrolled to couple the headset to the line 124. The hold indication168 is cleared, and any alarm and release warning conditions arecleared. If the depressed unit key 158e designates an MMU that isalready connected to another one of the retrieval consoles 100, then noaction is taken. Similarly, if the depressed one of the unit keys 158ecorresponds to an MMU which is not powered up, no action is taken.However, if the depressed unit key indicates an MMU which is notconnected to another console and which is powered up, the subroutine ofFIG. 14b disconnects the console from any MMU to which it was previouslyconnected and connects the console to the MMU corresponding to thedepressed unit key. The headset adapter 120 is controlled to ensure thatthe headset receives audio signals from the connected MMU. Then allmotion indicators and the release warning indicator are cleared, alongwith associated alarm conditions.

If the console being polled is connected to one of the MMU's and isindicating that a key has been depressed, then the subroutine of FIG.14c is executed. This subroutine responds appropriately to the hold,release, forward, and stop keys as shown in FIG. 14c. If the subroutineof FIG. 14c recognizes that one of the above-mentioned keys has not beenactivated, it then transfers control to the subroutine of FIG. 14bdescribed above.

In the event the console being polled is connected to an MMU and eitherno key is depressed or the forward or stop keys are depressed and theconsole is not on hold, then the subroutine of FIG. 14d is executed.This subroutine responds to reverse or forward actuation of the footpedal and, in addition, checks to ensure that forward or reverse tapemotion of the commanded MMU does not exceed predetermined limits withoutmultiple key or pedal activation. As shown in FIG. 14d, if reverse tapemotion has been commanded and if the console motion limit option hasbeen selected, then the subroutine checks to see whether a reversecommand switch (either the foot pedal 110 or the reverse key 158b) hasbeen depressed for more than 15 seconds. If not, reverse movement of theMMU is allowed to proceed; if so, the MMU is stopped and the consoleaudible alarm is activated if the audible alarm option has beenselected.

Similarly, if forward motion of the MMU has been commanded and theconsole motion limit option selected, the subroutine of FIG. 14d selectsa threshold depending upon whether a message is present upon theconnected MMU. If not, the time limit is set equal to 13 seconds of tapetravel. If so, the time limit is set equal to 60 seconds of tape travel.The subroutine then checks to see whether the forward tape motion haspersisted for a time period greater than the selected time limit. Ifnot, forward tape motion of the MMU is allowed to proceed. However, ifthe appropriate threshold has been exceeded, the MMU is stopped and theaudible console alarm is activated if that option has been selected.

If the subroutine of FIG. 14d does not detect activation of the footpedal 110 or the reverse switch on the console panel, and if the forwardlatch is not set, then the associated MMU is stopped and the subroutineof FIG. 14e is executed.

The subroutine of FIG. 14e checks to see if a key or foot pedal on theconsole being polled has been activated within the time limit set by theConsole Release Timeout switches 66. If not, a release warning conditionis set which will cause the activation of the release warning indicator168e. If the audible release warning option has been selected, theaudible console alarm is activated. Furthermore, if the warningcondition has existed for 30 seconds or more, the subroutine disconnectsthe console being polled from the previously connected MMU, then setsdata bits which will cause the headset adapter 120 to connect thetelephone headset 135 with the phone instrument 130. The poll of thenext console is then initiated.

2. Retrieval Console

The program of the retrieval console 100 is divided into fivesubprograms consisting of an initialization program, a foregroundsubprogram, and three interrupt routines.

a. Power On Initialization

This subprogram is executed whenever power is applied to the retrievalconsole 100 or the crash recovery circuit generates a processor reset.This subprogram disables all interrupts; tests and clears the RAM; setsthe stack pointer; initializes the RIOT; clears the I/O ports and setsthe timer mode; resets and disables the UART, initializes its mode andclears its receive buffer; clears the keyboard interface; initializesand enables the processor interrupts; and then jumps to the foregroundsubprogram.

b. Foreground Subprogram

The foreground subprogram monitors a software Receive Time Limit counterwhich determines when a transmission from the message processor 30 isincomplete. If the timer expires, the partial message is scrubbed. Inaddition, this subprogram supervises the transmission of data to themessage processor 30 when instructed to do so by the Receive CharacterInterrupt. Finally, this subprogram places the UART in the receive modewhen the response to the message processor 30 has been transmitted, sothat the UART is ready to receive another transmission from the messageprocessor 30.

c. Receive Character Interrupt

This subprogram is executed whenever the UART receives a character fromthe message processor 30 and the UART receiver has been previouslyenabled. This routine saves whatever CPU registers will be needed,resets the Receive Time Limit counter to prevent the foregroundsubprogram from scrubbing the message, assembles the message as eachcharacter is received from the message processor, and verifies themessage after it has been completed. Once the message has been verifiedthe console indicator state table is updated based on the receivedmessage. Then the current state of the footpedal switches are read andthe console switch state table is updated. The transmitting buffer forthe console's response to the message processor is then set up andflagged for the foreground subprogram to transmit it. CPU registers arerestored, the interrupt system is re-enabled and the subprogram returns.

d. Timer Interrupt

This subprogram is executed whenever the RIOT's timer generates a 50millisecond interrupt. This routine saves necessary CPU registers,increments the frequency count and updates variables used to flash theindicators, and updates the indicators based on the current values inthe indicator state table as adjusted by the Receive CharacterInterrupt. The volume control switches 158g, 158h are then read and thevolume control 156 and volume display 162 are updated. Finally, CPUregisters are restored, the interrupt system is re-enabled, and theroutine returns.

e. Keyboard Interrupt

This program is executed whenever a key is pressed on the console switchpanel 158 causing the keyboard interface 159 to generate an interrupt.This routine saves whatever CPUs are necessary, reads the key value fromthe keyboard interface, formats it, and merges it into the currentconsole switch state table, and then restores CPU registers, re-enablesthe interrupt system, and returns.

3. Console Message Processor Communications Protocol

The retrieval consoles 100 and the message processor 30 communicate bypassing relevant information back and forth in serial form. The messageprocessor 30 sends a selected one of the consoles 100, the indicatorstate information needed by the console, and the console 100 responds bysending to the message processor 30 the current console switch stateinformation.

The message processor 30 sends a 6 byte message in each transmission toa retrieval console 100, and each byte is 8 bits in length. The firstbyte indicates the commanded state of the Hold, Reverse, Stop, Forwardand Release Warning indicators 168a through 168e as well as the audiblealarm 170 and the state of the headset adaptor 120. The second and thirdbytes of the message provide information needed to control the messageindicators 164. Together, these two bytes indicate which of thefollowing four states each the message indicators 164 is in: On, Off,Slow Flash (1 Hertz, 50% duty cycle), Fast Flash (2 Hertz, 50% dutycycle). Similarly, the fourth and fifth bytes of the message indicatewhich of four states each of the serviced indicator 166 is in, asfollows: On, Off, Slow Flash (1 Hertz, 90% duty cycle), Fast Flash (2Hertz, 50% duty cycle). The 6th byte of the message is check sum for theprevious 5 bytes.

Responses from the retrieval consoles 100 to the message processor 30are 2-byte messages in which the first byte corresponds to the consoleswitch state and the second byte is a check sum which in this embodimentis equal to the first byte. The four least significant bits of the bytecorrespond to a key code which identifies the last key of the switchpanel 158 pressed, the next two bits indicate forward and reverse footpedal closures, and the two most significant bits are unused.

It is entirely possible that no console is attached to a particularcommunications line or that a console is disabled. The message processor30 is programmed to wait 3 character times for a response. If noresponse is received during that period, it will time out, scrub anyspurious message that may have been received, and proceed to the nextconsole.

4. Function Definitions

The foregoing discussion of the operation of the message retrievalsystem 20 is summarized and complemented by the function definitions ofTable I. The abbreviations used in Table I correspond to abbreviationsused elsewhere in this specification.

                  TABLE I                                                         ______________________________________                                        Name   Abbrev.  Definition                                                    ______________________________________                                        Message                                                                              MW       Solid indication on all                                       Waiting         Consoles for each MMU with                                                    untranscribed messages.                                       Message                                                                              MA       1 Hz (50% duty cycle) flashing Mes-                           Alert           sage indicator when MW condition                                              present for more than "Message                                                Alert" timeout. Cleared by trans-                                             cribing all messages.                                         Out of OT       2 Hz (50% duty cycle) flashing Mes-                           Tape            sage indicator when MMU is filled to                                          capacity.                                                     Unit   UD       2 Hz (50% duty cycle) flashing Mes-                           Disable         sage indicator when MA condition                                              present for more than "Unit Disable"                                          timeout, if this feature is enabled.                                          Also, particular unit is disabled                                             from taking more calls.                                                       Cleared by transcribing all messages.                         Unit   USV      Solid indication on all Consoles for                          Serviced        each MMU connected to another                                                 Console.                                                      Unit   UC       1 Hz (90% duty cycle) flashing Ser-                           Com-            viced indicator for MMU which this                            manded          Console is commanding.                                        Release                                                                              RW       2 Hz (50% duty cycle) flashing                                Warning         indication and optional audible                                               alarm on commanding Console when no                                           activity for greater than "Console                                            Release" timeout. Alarm volume user                                           controllable.                                                                 Cleared by F, FS, S, R, US, UR, or                                            UH. When on Hold, same except US                                              must be for Unit commanded.                                                   If RW persists for 30 sec., Console                                           is released from MMU.                                         Release                                                                              RWA      Setting in MPR to enable audible                              Warning         Release Warning alarm.                                        Audible                                                                       Stop   SM       Solid indication and optional                                 Motion          audible alarm on Console when motion                                          command exceeds limit.                                                        Cleared by motion release, UR, or                                             US.                                                                           Feature enabled by Console circuit                                            board jumper. Alarm volume user                                               controllable.                                                 Stop   SMA      Setting in MPR to enable audible                              Motion          Stop motion alarm.                                            Audible                                                                       Message                                                                              MAT      Setting in MPR to cause MA                                    Alert           condition.                                                    Timeout         Range: 1 min. to 99 hrs. 99 mins.                                             Zero setting disables feature.                                Console                                                                              CRT      Setting in MPR to cause RW condition                          Release         on commanding Console.                                        Timeout         Range: 1 min. to 99 mins. Zero                                                setting disables feature.                                     Unit   UDT      Setting in MPR to cause UD                                    Disable         condition.                                                    Timeout         Range: 1 min. to 99 hrs. 99 mins.                                             Zero setting disables feature.                                Unit   UDO      Setting in MPR to override UD                                 Disable         feature.                                                      Override                                                                      Unit   US       Console command to request                                    Select          connection to particular MMU.                                                 Releases any previous connection to                                           this Console. Acts within 250 ms.                                             Transfers telephone headset to                                                transcription.                                                Unit   UR       Console command to release                                    Release         connection to any MMU. Acts within                                            250 ms. Returns telephone headset                                             to phone instrument.                                          Forward                                                                              F        Console footpedal command to cause                                            forward tape motion. Acts within                                              125 ms. Accompanied by solid                                                  indication on Console. Momentarily                                            overrideable by R. Motion ceases                                              automatically if footpedal not                                                released in forward motion limit.                             Forward                                                                              FS       Console pushbutton command to                                 Start           initiate continuous forward tape                                              motion up to forward motion limit.                                            Accompanied by same indication as F.                                          Momentarily overrideable by R.                                                Timer reset by FS or R. Command                                               cancelled by S, F, or UH.                                                     Feature enabled by internal Console                                           jumper.                                                       Stop   S        Console pushbutton, command to stop                                           tape motion initiated by FS.                                  Reverse                                                                              R        Console footpedal or pushbutton                                               command to cause reverse tape                                                 motion. Acts within 125 ms.                                                   Accompanied by solid indication on                                            Console.                                                      Unit   UH       Console command to switch telephone                           Hold            headset back to phone instrument and                                          disable tape motion. Cancels FS                                               command. Accompanied by solid                                                 indication on Console. Released by                                            US for commanded unit or UR. Motion                                           commands F, FS, S, and R entered in                                           this mode, as well as UH itself,                                              clear the RW condition.                                       Headset                                                                              HT       Command from MPR to switch operator                           Transfer        headset over to MMU audio. Released                                           by UR and UH.                                                 Audible                                                                              AA       Command from MPR to activate audible                          Alarm           alarm in Console. Alarm is a one                                              second simple tone every 5 seconds.                           Volume VC       Internal Console commands to raise                            Control         and lower transcribe audio volume in                                          1 db steps over a 32 db range at 20                                           db/sec. Act as long as held.                                                  Accompanied by 8-segment bar graph                                            display, one bar per 4 db. Display                                            lit only when unit selected and not                                           on hold.                                                      ______________________________________                                    

C. MICROFICHE APPENDICES

The microfiche appendix to this specification includes Appendices A1-A7which provide additional information with regard to the hardware of themessage retrieval system 20 and Appendices B1 and B2 which provideprogram listings for the message processor and the retrieval console.There are 3 microfiche and a total of 138 frames. Table II describes thecontents of each of these appendices.

                  TABLE II                                                        ______________________________________                                        APPENDIX   DESCRIPTION                                                        ______________________________________                                        A1         Schematic diagram of Unit Interface Card                                      40.                                                                A2         Schematic diagram of Console Interface                                        Card 50.                                                           A3         Schematic diagram of Front Panel Board                                        60.                                                                A4         Schematic diagram of Master Controller                                        Card 70.                                                           A5         Schematic diagram of Message Processor 30.                         A6         Schematic diagram of retrieval console                                        100.                                                               A7         Table of principal components for A1-A6.                           B1         Listing of Message Processor program.                              B2         Listing of Retrieval Console program.                              ______________________________________                                    

In general, in the event of inconsistency, the appendices are to controlover the drawings and the discussion, and the drawings are to controlover the discussion.

D. OPERATION

The base units 24 and the MMU's 26 operate to record telephone messagesin the conventional manner. The retrieval consoles 100 are used by anoperator to control playback and rewinding of the message memory units26 and to request interconnection with any one of the message memoryunits 26. In addition, the retrieval consoles 100 provide considerableinformation as to the status of the message memory units.

With regard to this information provided by the retrieval console 100,the message processor 30 responds to the presence of untranscribedmessages on one of the MMU's by activating the red message indicators164 for that MMU on all of the consoles 100. If the MESSAGE PRESENTinput for an MMU has indicated the presence of recorded messages formore than the Message Alert Timeout set on the Front Panel Board 60, themessage indicator 164 will flash at 1 Hz until all messages are cleared.If such an alert has been present for more than the Unit Disable Timeoutset on the Front Panel Board 60, the message indicator 164 will flash at2 Hz and the MMU 26 and the associated base unit 24 will be preventedfrom taking further calls until all messages are transcribed from theMMU 26. Also, whenever an MMU 26 is filled to capacity, the associatedmessage indicator 164 will flash at 2 Hz. Both the message alert andunit disable features can be defeated by setting the associated switcheson the Front Panel Board 60 to zero. For convenience, the unit disablefeature may also be defeated by the unit disable override switch 168c onthe Front Panel Board 60.

In order to transcribe messages stored on one of the MMU's 26, theoperator presses the appropriate unit button 158e and if no otherconsole is servicing that MMU the message processor 30 connects theconsole to the MMU. The serviced indicator 166 (green) for that MMU isthen illuminated on all consoles. At the console to which the MMU isconnected (the commanding console) the respective serviced indicator 166flashes at 1 Hz (90% duty cycle). Tape motion may now be controlled bythe operator by pressing the forward and reverse foot pedal controls orswitches which are signalled by matching indicators on the console.Recorded messages from the MMU may be heard through the telephoneheadset or handset 135, or a conventional transcription headset orearpiece. The operator sets the preferred volume by pressing the volumecontrol switches 158g,158h, which raise or lower the volume as long asthey are depressed. The volume control switches 158g,158h scan the fullrange of 32 digital steps in about 1.5 seconds. The commanded volume isshown as a bar graph on the display 162. Eight segments are provided,one for every four volume steps. The volume display 162 is activatedonly when an MMU is selected and not on hold. When finished with oneMMU, the operator can then press the unit release switch 158f or selectanother MMU via one of the unit switches 158e.

The operator's control of tape motion is subject to constraints imposedby the message processor 30. The forward and reverse foot pedal controlsand the reverse switch 158b act only as long as they are held. Theforward switch 158d is enabled by an internal jumper in the console 100and it initiates forward motion which continues until the stop switch158c is depressed or until the forward limit has elapsed as explainedbelow.

In addition, a tape motion limiting feature is enabled by an internaljumper option in the console 100. With this option selected, continuousforward motion is limited to 60 seconds if the message indicator 164 forthe commanded MMU is activated and 13 seconds if it is not. Similarly,continuous reverse motion is limited to 15 seconds. If any of theselimits is exceeded or tape motion on the associated MMU is stopped, thecommanding console is controlled to activate the stop indicator 168c andto sound an optional audible alarm 170 until the control is released.The audible alarm for this feature is enabled by the option switch 68bon the Front Panel Board 60. In this embodiment tape speed in reverse isfour times that of tape speed in forward, and thus, the limits forforward and reverse motion are identical. The MMU's of this embodimentreset the MESSAGE PRESENT input during transcription of a last recordedmeassage while the last 13 seconds of transcription of the last recordedmessage is completed, and this causes the associated message indicatorto be turned off during the last 13 seconds of transcription of the lastrecorded message. The 13-second limit is for these situations in whichthe message indicator is not activated, and it allows an operator totranscribe the last 13 seconds of tape between the recording andtranscription heads without inadvertently playing back excessive tapeand thereby losing part of a next recorded message.

In addition, the reverse foot pedal or the reverse switch 158bmomentarily overrides the forward switch 158d. The forward foot pedalcancels the forward switch 158d. To resolve contradictory simultaneousinputs, tape motion command priority is (1) reverse, (2) forward footpedal, (3) forward switch.

If a commanding console does not issue a tape motion command in a timeequal to the Console Release Timeout set on the Front Panel Board 60,the release warning indicator 168e is caused to flash at 2 Hz and anoptional audible alarm is sounded until a motion command for the unitselected is received. If 30 seconds of a warning condition elapses, themessage processor 30 disconnects the previously connected MMU from thecommanding console and this MMU is then made available to otherconsoles. This feature is defeatable by setting the Console ReleaseTimeout switches to zero on the Front Panel Board 60. The audible alarmfor this feature is enabled by the switch 168a on the Front Panel Board60. The audible alarm in this embodiment is a one-second simple tonerepeated every 5 seconds. The alarm transducer 170 at each console isenabled by an internal jumper, and its volume is adjustable by anexternally accessible control.

The phone headset or handset 135 when used for transcription isautomatically switched to transcribe when a unit select switch 158e ispressed. If the operator desires to take a call live, the phone headset135 can be connected to the telephone instrument 130 by pressing thehold switch 158a. The phone headset 135 is returned to the transcriptionmode by pressing the appropriate unit select switch 158e again. The holdindicator 168a is activated as long as the MMU is on hold. Even thoughforward and reverse commands to not cause tape motion when the consoleis in the hold mode, they still act to clear a release warningcondition. The forward switch command 158d is cancelled by the unit holdcommand 158a.

All commands and indications are transmitted over a serial data linkbetween the message processor 30 and the consoles 100 at 19,200 bits persecond. In the event of a communications line failure between a console100 and the message processor 30, tape motion on the MMU commanded bythat console will cease within 1 second of the failure. Furthermore, ifthe line remains dead for 20 seconds, the MMU will be disconnected andmade available to other consoles.

Both the message processor 30 and the consoles 100 include circuitry torecover from random or spurious crashes. The run indicators on bothunits report on the condition of the electronics: a steady indicatorimplies that power is present and that the program is running, aflashing indicator indicates that power is present but the device ispermanently crashed, and no indicator implies no power. A crash of oneof the consoles 100 will only alter the volume setting. A crash of themessage processor 30 will stop all tape motion, release all consoles,and reset all accumulated time to zero. Operators should then reselectthe MMU's 26 they were working on and continue as before.

From the foregoing, it should be apparent that a message retrievalsystem has been described which provides important advantages. A singlespeaker such a headset or a handset is used by the operator both totranscribe recorded messages and to conduct live telephoneconversations. The speaker is automatically switched in mode tocorrespond to the mode of the retrieval console. In addition, themessage processor insures that a commanded MMU remains linked to aconsole even when the MMU is placed on hold and the console is used forlive telephone conversations. This feature of the system allows anoperator to interrupt transcription to conduct a live telephoneconversation and then to return to the interrupted transcription.

In order to insure that a console does not monopolize an MMU, theprocessor automatically disconnects a commanded MMU from its console inthe event the console has not commanded the MMU within a preset timeperiod. The processor also controls a warning on the console prior todisconnecting the console from the MMU in order to allow an operator totake action to preserve a connection.

Yet another feature of this invention is that action is automaticallytaken in the event recorded messages on the MMU's age excessively priorto transcription. In the preferred embodiment described above thisaction is to disable the MMU from recording further messages until allpreviously recorded messages have been transcribed. In alternateembodiments, the system may take other action, such as changing theprerecorded message of the base unit to indicate a longer callback timeto the telephone callers, or automatically interconnecting additionalretrieval consoles to speed message transcription.

Moreover, the system described above automatically controls playback andrewind motion of the MMUs to substantially prevent an operator frominadvertently playing back or reversing tape motion for an excessiveperiod of time without continuous activity.

Each of these features and advantages can be used separately andindependently of the others. However, the preferred embodiment describedabove is particularly efficient in that it provides all of theseadvantages.

Of course, it should be understood that a wide range of changes andmodifications to the preferred embodiment described above will beapparent to those skilled in the art. For example, the message processormay monitor other parameters than the MESSAGE PRESENT input from an MMUin order to gauge the age of recorded messages. The time a message isrecorded can be recorded on an MMU along with the message, and themessage processor can use this recorded time to perform the functionsdescribed above. U.S. Pat. No. 4,338,494 discloses hardware suitable foruse in such an alternate embodiment.

In addition, this invention is not limited to use with base units andmessage memory units of the type described above. For example, thisinvention can readily be adapted for use with a computer controltelephone answering and message recording system in which both themessages played back to callers and the recorded caller messages frommultiple telephone lines are recorded in a single computer memorysystem. As used herin, the term "message memory unit" is intended in itsbroad sense to encompass any storage medium for recorded messages,including secluded locations, in such a computer memory system.Similarly, as used herein, the term "telephone answering machine" isintended in its broad sense to cover any mechanism for answering aringing telephone line, including a mechanism controlled by a centralcomputer.

Furthermore, the number of MMU's or retrieval consoles can be varied asneeded to suit the individual application. Furthermore, other hardwareapproaches and other programs can be used to implement the functionsdescribed above. It is therefore intended that the foregoing detaileddescription be regarded as illustrative rather than limiting, and thatit be understood that it is the following claims, including allequivalents, which are intended to define the scope of this invention.

We claim:
 1. In a message retireval system of the type comprising aplurality of telephone answering machines and a plurality of messagememory units coupled to the answering machines, each of the messagememory units including means for storing a plurality of messages, theimprovement comprising:at least one retieval console coupled to themessage memory units to permit an operator at the retrieval console tocommand playback of messages stored on the message memory units; meansfor automatically monitoring a parameter indicative of the age ofmessages stored in the message memory units and for automaticallygenerating an alarm signal in the event the parameter reaches a range ofvalues indicative of excessive delays between storage and playback ofmessages stored in the message memory units; and means for automaticallymodifying the system in response to the alarm signal to adapt the systemto excessive delays between message storage and playback.
 2. Theinvention of claim 1 wherein the monitoring means monitors the parameterfor each of the message memory units separately; wherein the alarmsignal indicates which of the message memory units triggered the alarmsignal; and wherein the modifying means comprises:means for preventingthe one of the message memory units which triggered the alarm signalfrom recording additional messages until after excessive delays betweenstorage and playback of messages stored in said one of the messagememory units have been eliminated.
 3. In a message retrieval system ofthe type comprising a plurality of telephone answering machines and aplurality of message memory units coupled to the answering machines,each of the message memory units including means for storing a pluralityof messages, the improvement comprising:at least qne retrieval consolecoupled to the message memory units to permit an operator at theretrieval console to command playback of messages stored on the messagememory units; a message processor interconnected between the messagememory units and the console, said message memory units generatingrespective signals indicative of the presence of a stored message;means, included in the processor, for automatically monitoring thesignals and for generating an alarm when one of the signals has beenpresent for more than a first time interval; means, included in theprocessor, for automatically preventing the respective message memoryunit from recording additional messages when the one of the signals hasbeen present for more than a second time interval, longer than the firsttime interval.
 4. In a message retrieval system of the type comprising aplurality of telephone answering machines and at least one messagememory unit coupled to the answering machines, each of the messagememory units including means for storing a plurality of messages, theimprovement comprising:at least one retrieval console coupled to each ofthe message memory units to permit an operator at the retrieval consoleto command playback of messages stored on each of the message memoryunits; means for automatically monitoring a parameter indicative of theage of messages stored in the at least one message memory unit and forautomatically generating an alarm signal in the event the parameterreaches a range of values indicative of excessive delays between storageand playback of messages stored in the at least one message memory unit;and means for automatically modifying the system in response to thealarm signal to adapt the system to excessive delays between messagestorage and playback.
 5. The invention of claim 4 wherein the modifyingmeans prevents the at least one message memory unit from recordingadditional messages until after excessive delays between storage andplayback of messages in the message memory unit have been eliminated. 6.In a message retrieval system of the type comprising a plurality oftelephone answering machines and at least one message memory unitcoupled to the answering machines, each of the message memory unitsincluding means for storing a plurality of messages, the improvementcomprising:at least one retrieval console coupled to each of the messagememory units to permit an operator at the retrieval console to commandplayback of messages stored on each of the message memory units; amessage processor interconnected between the at least one message memoryunit and the console, said at least one message memory unit generating asignal indicative of the presence of a stored message; means, includedin the processor, for automatically monitoring the signal and forgenerating an alarm when the signal has been present for more than afirst time interval; means, included in the processor, for automaticallypreventing the at least one message memory unit from recordingadditional messages when the signal has been present for more than asecond time interval, longer than the first time interval.